As communications technologies develop, the 3rd Generation Partnership Project (3GPP for short) has studied and standardized the 3G Long Term Evolution (LTE for short) technology, expecting to obtain a higher speed, a larger capacity, and better user performance. In an initial phase of LTE deployment, an LTE network is deployed only in a hotspot, but a 2G/3G network covers all areas. In an area in which various wireless networks overlap or adjoin each other, when a UE (user equipment) moves back and forth between an LTE network and a 2G/3G network, the UE needs to perform inter-system cell reselection, where inter-system cell reselection each time causes a location update process of the UE, so that information about a location with which the UE registers in a core network is updated, thereby increasing a large amount of signaling load in the network and on an air interface.
To resolve the foregoing problem, an idle mode signaling reduction (ISR for short) mechanism is introduced in 3GPP. After the ISR mechanism is activated, when the UE moves in a coverage with which the UE has registered, the UE does not need to perform a location update even though the UE crosses different standards. In addition, if a network needs to page the UE, paging is performed on the UE in cells in location areas with which the UE registers in different network standards. However, the UE can camp on only one network standard to listen to a paging message in one cell, and therefore, a waste of system air interface resources is caused in the prior art when paging is performed in all location areas with which the UE registers. Therefore, an optimization method for paging UE in hybrid network standards needs to be proposed.